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Wyszukujesz frazę "Fourier" wg kryterium: Temat


Tytuł:
Discrete Fourier transform based pattern classifiers
Autorzy:
Hui, S.
Żak, S. H.
Powiązania:
https://bibliotekanauki.pl/articles/202074.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pattern classification
multidimensional discrete Fourier transform
DFT
Fourier coefficients
Opis:
A technique for pattern classification using the Fourier transform combined with the nearest neighbor classifier is proposed. The multidimensional fast Fourier transform (FFT) is applied to the patterns in the data base. Then the magnitudes of the Fourier coefficients are sorted in descending order and the first P coefficients with largest magnitudes are selected, where P is a design parameter. These coefficients are then used in further processing rather than the original patterns. When a noisy pattern is presented for classification, the pattern’s P Fourier coefficients with largest magnitude are extracted. The coefficients are arranged in a vector in the descending order of their magnitudes. The obtained vector is referred to as the signature vector of the corresponding pattern. Then the distance between the signature vector of the pattern to be classified and the signature vectors of the patterns in the data base are computed and the pattern to be classified is matched with a pattern in the data base whose signature vector is closest to the signature vector of the pattern being classified.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 1; 15-22
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some classical function systems in separable Orlicz spaces
Autorzy:
Finet, C.
Tkebuchava, G.
Powiązania:
https://bibliotekanauki.pl/articles/1221051.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Fourier
Fourier-Walsh series
Paley function
Haar system
separable Orlicz space
Opis:
The boundedness of (sub)sequences of partial Fourier and Fourier-Walsh sums in subspaces of separable Orlicz spaces is studied. The boundedness of the shift operator and Paley function with respect to the Haar system is also investigated. These results are applied to get the analogues of the classical theorems on basicness of the trigonometric and Walsh systems in nonreflexive separable Orlicz spaces.
Źródło:
Studia Mathematica; 1996, 121, 2; 193-205
0039-3223
Pojawia się w:
Studia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel tool for Non Destructive Testing using frequency analysis of IR image sequences
Autorzy:
Więcek, P.
Strąkowska, M.
Powiązania:
https://bibliotekanauki.pl/articles/114539.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
IR thermography
wavelet
Fourier
short-time Fourier transforms
functional thermal imaging
Opis:
In this paper, a novel methodology and a software tool for advanced image processing of thermal image sequences are presented. The software implements 1-D Fourier, short-time Fourier and wavelet transforms. The tool uses temperature variation in time for each pixel in the sequence of IR images. It is dedicated to Non Destructive Testing (NDT) testing and the functional time-dependent thermal imaging, e.g. for screening in medical diagnosis. The overall methodology is based on 2-stage analysis. The first, preliminary one is to estimate the right scale/frequency and the moment in time for the final frequency analysis. It can simplify characterization of materials and detection of cracks and defects.
Źródło:
Measurement Automation Monitoring; 2015, 61, 6; 219-222
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of supra-harmonics through signal processing methods in smart grids
Autorzy:
Yalcin, T.
Ozdemir, M.
Kostyla, P.
Leonowicz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/136245.pdf
Data publikacji:
2017
Wydawca:
EEEIC International Barbara Leonowicz Szabłowska
Tematy:
ensemble empirical mode decomposition
power quality
Fourier analysis
Short Time Fourier Transformation
Opis:
Nowadays supra-harmonic distortion studies are gaining attention day by day in power quality research area. When handling communication systems especially Power Line Carrier (PLC) systems in frequency range 2-150 kHz, they are suitable for causing electromagnetic interference (EMI) to other systems. This study shows results of analysis employing advanced method called ensemble empirical mode decomposition (EEMD) to describe supra-harmonic distortion. Unlike the traditional method (short time fourier transform-STFT), EEMD gives extensive representation for supra-harmonic components.
Źródło:
Transactions on Environment and Electrical Engineering; 2017, 2, 2; 80-85
2450-5730
Pojawia się w:
Transactions on Environment and Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie algebr hiperzespolonych w przetwarzaniu sygnałów
Application of hypercomplex algebras in signal processing
Autorzy:
Błaszczyk, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/134792.pdf
Data publikacji:
2016
Wydawca:
ADVSEO
Tematy:
hypercomplex algebras
quaternion Fourier transform
octonion Fourier transform
system analysis
partial differential equations
Opis:
The subject of this paper is the application of hypercomplex algebras (in particular quaternions and octonions) in the analysis of time-invariant linear systems. We present the Cayley-Dickson construction of hypercomplex algebras and its important properties. Moreover, we formulate the concept of quaternion and octonion Fourier transform and their properties important from the signal processing point of view. We present an overview of known quaternion Fourier transform applications in the analysis of systems and partial differential equations of two variables. We also point out the direction of further work in the subject of application of the octonion Fourier transform in system analysis and analysis of partial differential equations of three variables. Such considerations are possible thanks to recently proved properties of octonion Fourier transform, which are also stated in this paper.
Źródło:
Technical Issues; 2016, 3; 13-18
2392-3954
Pojawia się w:
Technical Issues
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of sonar detection signal based on fractional Fourier transform
Autorzy:
Wang, B.
Tang, J.
Yu, F.
Zhu, Z.
Powiązania:
https://bibliotekanauki.pl/articles/259724.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
fractional Fourier transform
watermark
sonar
Opis:
Aiming at the source of underwater acoustic emission, in order to identify the enemy emission sonar source accurately. Using the digital watermarking technology and combining with the good time-frequency characteristics of fractional Fourier transform (FRFT),this paper proposes a sonar watermarking method based on fractional Fourier transform. The digital watermark embedding in the fractional Fourier transform domain and combined with the coefficient properties of the sonar signal in the fractional Fourier transform to select the appropriate watermark position. Using the different characteristics of the signals before and after embedding, an adaptive threshold was set for the watermark detection to realize the discrimination of sonar signals. The simulation results show the feasibility and has better resolution and large watermark capacity of this method, while the robustness of the watermark is better, and the detection precision is further improved.
Źródło:
Polish Maritime Research; 2018, S 2; 125-131
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Synchrophasor Estimatioo Errors
Autorzy:
Łukowicz, M.
Cygan, S.
Powiązania:
https://bibliotekanauki.pl/articles/410593.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
synchrophasor estimation
dynamic phasor
Fourier transform
Taylor Fourier series
phase locked loop
dynamic filter
Opis:
This papers discusses the analytical analysis of the syochrophasor estimation employed in electrical systems. Short time Fourier trsnsform with the phase locked loop and Taylor Fourier series are analyzed for signals relating to different states which may occor in real power systems. The object is the accurate phasor estimation regardless of the shape of input signal, what for some signal types is cumbersome. As a result of active and reactive power disturbance in a power system, the frequency deviation and amplitude fluctuations may appear in power system signals. As a consequences of short circuits or overvoltages signal changes occur. Ibis leads to unacceptable errors in short time Fourier transform resulting from Fourier transform properties. This paper presents character of occurring errors and their consequences individually for any signal deviation.
Źródło:
Present Problems of Power System Control; 2017, 8; 5-22
2084-2201
Pojawia się w:
Present Problems of Power System Control
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polyhedral summability of multiple Fourier series (and explicit formulas for Dirichlet kernels on $^n$ and on compact Lie groups)
Autorzy:
Travaglini, Giancarlo
Powiązania:
https://bibliotekanauki.pl/articles/967329.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
polyhedral Dirichlet kernels
multiple Fourier series
Fourier series on compact Lie groups
Lebesgue constants
Opis:
We study polyhedral Dirichlet kernels on the n-dimensional torus and we write a fairly simple formula which extends the one-dimensional identity $∑_{j=-N}^N e^{ijt} = sin((N+(1/2))t) / sin((1/2)t)$. We prove sharp results for the Lebesgue constants and for the pointwise boundedness of polyhedral Dirichlet kernels; we apply our results and methods to approximation theory, to more general summability methods and to Fourier series on compact Lie groups, where we write an asymptotic formula for the Dirichlet kernels.
Źródło:
Colloquium Mathematicum; 1993, 65, 1; 103-116
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The New Insight into the Theory of 2-D Complex and Quaternion Analytic Signals
Autorzy:
Snopek, K. M.
Powiązania:
https://bibliotekanauki.pl/articles/226235.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
2-D Fourier transform
quaternion Fourier transforms
2-D Hilbert transforms
2-D analytic signals
Opis:
The paper presents the overview of the theory of 2-D complex and quaternion analytic signals with the 1st-quadrant spectrum support. Both signals are expressed as complex/hypercomplex sums of partial and total 2-D Hilbert transforms. Moreover, starting with the definition of 2-D complex and quaternion Fourier transforms, the 2-D Hilbert transforms are derived in the form of sums of parts of different parity with respect to signal-domain variables. Some new relations for Hilbert quaternion spectra have been derived. The paper is illustrated with the example of the 2-D separable Cauchy signal.
Źródło:
International Journal of Electronics and Telecommunications; 2011, 57, 3; 285-291
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A characterization of completely bounded multipliers of Fourier algebras
Autorzy:
Jolissaint, Paul
Powiązania:
https://bibliotekanauki.pl/articles/967649.pdf
Data publikacji:
1992
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
representation
C*-algebra
multiplier
Fourier algebra
Źródło:
Colloquium Mathematicum; 1992, 63, 2; 311-313
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The heat equation on time scales
Autorzy:
Cuchta, Tom
Ferreira, Rui A. C.
Powiązania:
https://bibliotekanauki.pl/articles/29519378.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
heat equation
time scales
Fourier transform
Opis:
We present the use of a Fourier transform on time scales to solve a dynamic heat IVP. This is done by inverting a certain exponential function via contour integral. We include some specific examples and directions for further study.
Źródło:
Opuscula Mathematica; 2023, 43, 4; 475-491
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Steganographic algorithm of hiding information in sound based on Fourier transform and masking
Autorzy:
Kozieł, G.
Powiązania:
https://bibliotekanauki.pl/articles/206286.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
keywords steganography
hidden communication
Fourier transform
Opis:
A new steganographicmethod based on Fourier transform is proposed. Data is attached in the frequency domain within the limits of the audible band. Masked frequencies are used to conceal information in order to make the changes inaudible for human ear. This approach allows for modification in the sound frequency band only, and does not require any additional modifications. It also allows for concealing information efficiently, minimizing the number of changes and gaining robustness with respect to popular sound transformations.
Źródło:
Control and Cybernetics; 2011, 40, 4; 1231-1247
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie transformaty Fouriera w algorytmie segmentacji standardowych obrazów koronarograficznych
Application of Fourier transform in the standard coronarography images segmentation algorithm
Autorzy:
Syrycki, M.
Mazurek, W.
Stachurska, A.
Powiązania:
https://bibliotekanauki.pl/articles/261635.pdf
Data publikacji:
2009
Wydawca:
Politechnika Wrocławska. Wydział Podstawowych Problemów Techniki. Katedra Inżynierii Biomedycznej
Tematy:
transformata Fouriera
koronografia
Fourier transform
coronography
Opis:
W pracy przedstawiono zastosowanie analizy Fouriera do efektywnej segmentacji obrazów drobnych naczyń wieńcowych w standardowych obrazach koronarograficznych.
Application of Fourier analysis for segmentation of standard coronarography images of smali coronary vessels, is discussed.
Źródło:
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna; 2009, 15, 1; 58-60
1234-5563
Pojawia się w:
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Discrete Fourier transform and permutations
Autorzy:
Hui, S.
Żak, S. H.
Powiązania:
https://bibliotekanauki.pl/articles/202022.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
discrete Fourier transform
DFT
DFT invariants
Fourier coefficients
permutations
DFT coefficient magnitudes
circulant matrix
pattern recognition
Opis:
It is well known that the magnitudes of the coefficients of the discrete Fourier transform (DFT) are invariant under certain operations on the input data. In this paper, the effects of rearranging the elements of an input data on its DFT are studied. In the one-dimensional case, the effects of permuting the elements of a finite sequence of length N on its Discrete Fourier transform (DFT) coefficients are investigated. The permutations that leave the unordered collection of Fourier coefficients and their magnitudes invariant are completely characterized. Conditions under which two different permutations give the same DFT coefficient magnitudes are given. The characterizations are based on the automorphism group of the additive group ZN of integers modulo N and the group of translations of ZN. As an application of the results presented, a generalization of the theorem characterizing all permutations that commute with the discrete Fourier transform is given. Numerical examples illustrate the obtained results. Possible generalizations and open problems are discussed. In higher dimensions, results on the effects of certain geometric transformations of an input data array on its DFT are given and illustrated with an example.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 6; 995-1005
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A stationary phase formula for exponential sums over $ℤ/p^{m}ℤ$ and applications to GL(3)-Kloosterman sums
Autorzy:
Dąbrowski, Romuald
Fisher, Benji
Powiązania:
https://bibliotekanauki.pl/articles/1390918.pdf
Data publikacji:
1997
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
exponential sums
Fourier coefficients of automorphic forms
Źródło:
Acta Arithmetica; 1997, 80, 1; 1-48
0065-1036
Pojawia się w:
Acta Arithmetica
Dostawca treści:
Biblioteka Nauki
Artykuł

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